Electric cleaner



i'xg. 5, 196.9 y TsuNEo KoBAYAsHl ET AL 3,458,392

ELECTRIC CLEANER 2 Sheets-Sheet 1 Filed Nov. 20, 1967 5 5@ fil UnitedStates Patent O U.S. Cl. 15--327 4 Claims ABSTRACT F THE DISCLOSURE Avacuum cleaner of the type in which a dust bag and an electric blowerare provided in a body thereof and the dust sucked into the body of thecleaner through a exible hose connected to the suction port of the bodyis collected in said dust bag, said vacuum cleaner being characterizedin that a switch provided at the grip portion of said flexible hose isconnected to the control winding of a variable reactor in the 'body ofthe cleaner through a pair of leads, while a high voltage relay adaptedto be actuated by said switch to open and close the main circuit of saidelectric blower is connected to the main winding of said variablereactor in series, whereby the low voltage circuit of a remote controlcircuit for a motor including said switch is electrically separated fromthe main circuit of the electric blower.

Background of the invention ln general, in the use of a vacuum cleanerof the type which comprises a body with a dust bag and an electricblower accommodated therein and a flexible hose removably connected tothe suction port of said body at one end and having a floor nozzleconnected to the other end, the vacuum cleaner sucks dust into the dustbag and collects the same in said dust bag through the floor nozzle andthe flexible hose by the suction of said electric blower while beingdragged on the floor by the operator by way of the ilexible hose.

In the vacuum cleaners of the type described, it has been a commonpractice to provide a switch at the grip portion of the flexible hose,in addition to the switch provided on the body of the vacuum cleaner, soas to enable the operator to control the operation of the electricblower remotely at said grip portion without obliging the operator toreach after the switch on the body of the cleaner each time the electricblower is to be set in motion or stopped. Further, in the conventionalvacuum cleaners, since the terminal ends of the electric circuit in thebody of the cleaner, through which the switch on the flexible hose iselectrically connected to said circuit, are exposed when the flexible-hose is disconnected from the suction port, a provision is made to dropthe voltage in said electric circuit to such a level as not to endangerthe operator.

According to the present invention, the remote control circuitcomprising leads embedded in the exible hose and electrically connectingthe switch, provided at the grip portion of the flexible hose, with theelectric circuit in the body of the cleaner, is partly operated at a lowvoltage, so as not only to ensure the safety of the operator but also toprevent the high voltage in the main circuit of the electric blower frombeing impressed on said remote control circuit even when a faultycondition occurs at any portion of said remote control circuit, wherebythe safety of the operator is further enhanced.

ice

In the conventional vacuum cleaners of the type described, the switchprovided at the grip portion of the flexible hose, adapted to beremovably connected to the suction port of the body of the cleaner, isconnected to the secondary winding of a step down transformer in thebody, through a pair of leads embedded in said ilexible hose and aconnector provided in the body of the cleaner, and a low voltage relayto open and close the main circuit of the electric blower in the body ofthe cleaner is connected in series to said secondary winding of the stepdown transformer, to form a remote control circuit. Thus, the voltageimpressed on the remote control circuit, comprising the switch on theflexible hose, the connector in the body of the cleaner, the secondarywinding of the step down transformer and the low voltage relay, isdropped to a safety level by the step down transformer. However, sucharrangement is not entirely satisfactory because, if the low voltagerelay becomes faulty, causing shorting of the main circuit of theelectric blower, a serious accident will result. Namely, since the highvoltage is impressed on the entire secondary circuit of the step downtransformer, there is the danger of the low voltage relay and thesecondary winding of the step down transformer being burnt or theoperator being struck by electricity due to failure in insulation of theleads in the flexible hose or the switch on said flexible hose.

In order to avoid such a danger, it has been necessary to provide aStrong insulation between the contacts of the switch of the low voltagerelay to open and close the main circuit of the electric blower and anexciting winding on which a low voltage is impressed. It is for thisreason that most of the conventional vacuum cleaners are large in sizeand expensive.

Another problem of the conventional vacuum cleaners having a remotecontrol circuit of the type described is that, since the secondarywinding of the step down transformer and the low voltage relay areconnected in series, the current flowing through the low voltage relayis decreased by the impedance of said relay, when the switch on theflexible hose is closed. Therefore, there exists a tendency that theoperation of the low voltage relay becomes unstable. In order to obtaina stable operation of the low voltage relay, it is necessary to maintaina high induced electromotive force in the secondary winding but thiswill result in a high voltage at the connection in the body of thecleaner, giving a detrimental affect on the operation of the cleaner.

Still another problem is that the residual magnetism in the magneticcircuit keeps the main circuit closed even after the switch is opened tointerrupt the current flowing through the exciting winding of the lowvoltage relay. The elimination of such problem has necessitated the use`of high quality material for the core or the provision of ashort-circuit winding in the magnetic circuit to erase the residualmagnetism or the provision of a small space in said magnetic circuitand, as a result, the vacuum cleaner has been rendered complicated inconstruction and expensive.

Still another drawback of the low voltage `relay is that the excitingwinding is large in size and costly, because it is required to beoperative at a low voltage and, in order to reduce the impedance, itmust be formed with a wire with a large diameter wound in a large numberof turns.

As described hereinabove, the conventional vacuum cleaners possess anumber of shortcomings which all stern from the type of the remotecontrol circuit in which the low voltage relay to open and close themain circuit of the electric blower is connected to the secondarywinding of the transformer.

Summary of the invention The vacuum cleaner of this invention has aremote control circuit for the electric blower, which eliminates anumber of drawbacks of the conventional vacuum cleaners as set forthhere above.

Namely, according to the present invention, the switch provided at thegrip portion of the flexible hose, connected to the suction port of thebody of the cleaner, is electrically connected to the control winding ofa variable reactor provided in said body through a pair of leadsembedded in said flexible hose and the connector in the body, while thehigh voltage relay to open and close the main circuit of the electricblower in the body upon actuating `said switch is electrically connectedto the main winding of said variable reactor in series, so as to form aremote control circuit.

Therefore, by properly selecting the number of turns of the main andcontrol windings of the variable reactor, the voltage to be impressed onthe control winding can be controlled to a safe level and the operatorcan handle the vacuum cleaner with much safety, even when the connectorbetween the leads leading to the switch on the ilexible hose and theelectric circuit in the body of the cleaner is exposed after saidilexible hose is disconnected from said body.

Further, according to the present invention, the control `winding of thevariable reactor is completely independent of the high voltage relayeven when the high volta-ge relay is shorted `with the main circuit ofthe electric blower on which the high voltage is impressed, since saidhigh voltage relay is connected in series to the main winding of thevariable reactor which is impressed with a source voltage.

Namely, the remote control circuit composed of the switch on theflexible hose, the connector in the body of the cleaner and the controlwinding of the variable reactor, can be completely separated from themain circuit of the electric blower electrically under any condition, sothat the electrical insulation can be maintained positively and thesafety of the operator can be assured.

The primary object of the present invention is to completely eliminatethe electric shock from which the operator suffers upon occurrence of afaulty condition in the high voltage relay which opens and closes themain circuit of the electric blower directly, by electrically isolatingsaid high voltage relay from the electric circuit composed of theconnector in the cleaner body connected to the control winding of thevariable reactor and the switch at the grip portion of the flexible hoseelectrically connected to said connector.

Another object of the present invention is to enable a high voltagerelay to be used in a vacuum cleaner, which can be insulated easily andis compact in size and cheap in price, by connecting said high voltagerelay to the main winding of the variable reactor.

Still another object of the present invention is to provide a vacuumcleaner in which the electromotive force for the control lwinding of thevariable reactor is as low as about volts or lower, so that the operatorof the cleaner will not be struck by electricity when he inadvertentlytouches the connector in the body of the cleaner.

Still another object of the present invention is to provide a vacuumcleaner in which the high volta-ge relay is connected in series to themain winding of the variable reactor and thereby a slight current ismaintained in said winding even when the switch on the llexible hose isin an open position, whereby an erroneous operation of the cleanercaused by a residual magnetism is avoided.

Still another object of the present invention is to provide a vacuumcleaner in which the exciting winding of the high voltage relay isconnected in series to the main winding of the variable reactor, wherebythe voltage impressed on the main winding of the variable reactor ismaintained lower than a Source voltage and accordingly 4 the number ofturns of the main winding can be reduced, rendering the remote controlcircuit small in size and low in cost.

The other objects and advantages of the present invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings,

Brief description of the drawings FIG. 1 is a side elevation of thevacuum cleaner according to this invention, with the body thereof partlybroken away to show a high voltage relay and an electric blower,accommodated in said body and a part of a exible hose connected to thesuction port of said body;

FIG. 2 is a fragmentary plan view, in enlargement, of the exible hosewith an intermediate portion cut away;

FIG. 3 is a wiring diagram of the vacuum cleaner of this invention;

FIG. 4 is a cross sectional View showing a variable reactor and the highvoltage relay mounted on a base and enclosed in a casing;

FIGS. 5 and 6 are charts illustrating the operation of the variablereactor; and

FIG. 7 is a chart illustrating the operation of the remote controlcircuit.

Description of the preferred embodiment Referring to FIG. l, the vacuumcle'aner generally indicated by 1 has a dust bag 2 disposed in the frontportion and an electric blower 3 mounted in the rear portion of theinterior thereof. The dust bag 2 is made with an air permeable fabric soas to collect dust only therein by permitting air to pass therethrough,and is mounted in the cleaner in such a manner that it can be taken outfrom the cleaner 1 when the dust collected therein has reached a certainamount. The electric blower 3 is composed of a series A.C. motor 4 andfan blades (not shown) mounted on the rotary shaft (not shown) of saidmotor. The fan blades are enclosed in a casing 5 having air passageholes (not shown) bored in the front wall thereof and this casing 5 issupported at its periphery by brackets 7 and 7a, projecting inwardlyfrom the peripheral Wall of the body 1, through the intermediary of acushion member 6 such that it will not vibrate in the -body 1. Betweenthe dust bag 2 and the electric blower 3 is provided a dust bagsupporting member 8 which is secured to the inner peripheral wall of thebody 1 and serves to prevent the dust bag 2 from being drawn into theair passage holes in the casing 5 binding the fan blades, as well as toprovide for smooth passage of air through said air passage holes. Thefront opening of the body 1 is closed by a front cover 9 through whichthe -dust bag 2 is taken out from the body 1. The front cover 9 ishinged to the body 1 by a hinge 10 and is held in a closed position bylatch means which has one end rotatably secured to the body 1 and formedat the other end with a hook-shaped portion 12 for engagement with thefront cover 9. A suction port 13 is formed in the front cover 9, throughwhich dust and air are sucked into the body of the cleaner. An arm 17 isconnected to the front portion on the underside of the body 1, said armhaving a wheel 16 rotatably mounted to the free end thereof. Rear wheels18 are rotatably mounted to both sides of the rear portion of thebody 1. A power cord 19 is taken up on a cord winding reel (not shown)and has a plug 20 provided at the free end thereof. The power cord 19 isdrawn into or out of the body 1 through an opening 21 formed in saidbody. A handle 14 is provided with a vent hole 22 and a main switch 23for the electric lblower 3. A flexible hose 24 has a predeterminedlength and is provided at one end with a connecting tube 25 which isadapted to be removably connected to the suction port 13 in the body 1.As shown in FIG. 2, the connecting tube 25 is provided with a case 28with a press button 26 accommodated therein and a hook 27 is formedintegrally with the press button 26. The arrangement is such that whenthe press button 26 is depressed, the hook 27 is retracted in thecasing, whereas when the depression is removed from said button, thehook 27 projects above the casing.

In connecting the flexible hose 24 to the body 1 of the cleaner, theconnecting tube 25 is inserted into the suction -port 13 while havingthe hook 27 retracted in the case 28 by depressing the button 26 and,upon completion of the insertion, the depression is removed from thebutton, whereupon the hook 27 projects upwardly to engage the insidewall of the suction port 13 as shown in FIG. 1. A gri-p member 4'4connected to the other end of the ilexible hose 24 is provided thereonwith a low voltage switch 29 for the electric blower 3. This low voltageswitch 29 is connected to -a pair of leads embedded in the flexible hose24 as will be described later, which leads in turn are connected to aconnector 30, such as a pair of pins, projecting outwardly from the rearend wall of the case 28. When the connecting tube 25 of the flexiblehose 24 is inserted into the suction port 13, the connector 30 isbrought into contact with a connector 31 on the cleaner body side asshown in FIG. l and thereby the low voltage switch 29 is electricallyconnected to the electric circuit in the cleaner body 1. The grip member44 has a flexed tube 32 rotatably connected to the forward end thereof,to which an attachment such as a oor nozzle (not shown) is connected byway of a pipe, etc. (not shown). The cleaner body 1 has a case 33mounted therein as shown in FIG. 1, in which case are provided avariable reactor and a high voltage relay to be described later, whichdirectly opens and closes the main circuit of the electric blower 3.

Now, the electric circuit of the vacuum cleaner of the present inventionwill be described with reference to FIG. 3. A high voltage motorgenerally indicated by 4 cornprises an armature 4a and field windings4b, 4b having one ends connected to said armature and the other endsconnected to the terminal ends of a power cord 19 respectively. The mainswitch 23 on the cleaner body 1 is connected in series to the maincircuit 34 of the electric blower 3 which is encircled by the dottedline. The variable reactor 35 has its main winding 36 connected inparallel to the main circuit 34 of the electric blower, so that anextremely low voltage (about 20 v.) and a small current are induced inthe control winding 37 by the power source voltage. The control winding37 is connected to the connector 31 in the cleaner body. The excitingwinding 39 of the high voltage relay 38 is connected to the main winding36 of the variable reactor 35 in series. The high voltage relay 38 keepsthe high voltage switch open and is connected to the main circuit 34 ofthe electric blower 3 in parallel with the main switch 23, said highvoltage switch consisting 0f a movable contact 40 and a cooperatingfixed contact 41. The pair of leads 42, encircled by the dotted line,which are embedded in the flexible hose 24, have both ends connected tothe connector 30 on the flexible hose and the low voltage switch 29respectively. The broken line 43 indicates the remote control circuitfor the electric blower 3.

Referring now to FIG. 4, a base 44 is made of an electrical insulatingmaterial and has the variable reactor 35 and the high voltage relay 318mounted thereon, said high voltage relay 38 being secured to said baseby a screw 4S. The Case 33 is securely mounted on the base 44 by screws46 so as to enclose the variable reactor and the high voltage relaytherein to keep them from dust. The variable reactor 35 comprises aniron core 47 to form a magnetic circuit, a concentrical coil bobbin 48mounted on said iron core, and the main winding 36 and the controlwinding 37 wound on said coil bobbin 48 and insulated from each other byan insulating spacer 49, the number of turns of said control windingbeing smaller than that of the main winding.

The high voltage relay 38 comprises a boss 51, a coil bobbin 50, anexciting winding 39 wound on said coil bobbin, an L-shaped fixed member512 of a ferromagnetic material and a movable member 53. The magneticcircuit formed by said component parts is excited by the excitingwinding 39. A spring 54 is provided between one end of the fixed member52 and t-he corresponding end of the movable member 53 so as to keep themovable member 53 apart from the boss 5l when the exciting winding 39 isnot excited. A contact leaf spring 55 has one end secured to the movablemember 53 by a pin 56 and carries at the other end a movable contact40'. The coil bobbin 50 is provided with a fixed contact 41 in opposedrelation to said movable contact 40. The movable contact 40 and thefixed contact 41 are engaged with or disengaged from each other as themovable member S3 is attracted to or repulsed from the boss 5-1, therebyclosing o-r opening the main circuit 34 of the electric blower 3connected to the motor 4. The upward movement of the movable member 53is limited by a stopper 57. Reference numeral 58 indicates a shadingcoil.

`Because of the construction described above, when the flexible hose 24is connected to t-he suction port 13, the main circuit of the electricblower 3` and the remote control circuit 43 are connected to a powersource. If the low voltage switch 29 is open in this case, the impedanceof the variable reactor is composed of a reactance component inproportion to the second power of the number of turns and a resistancecomponent substantially in proportion to the eleven-tenth power of thenumber of turns. However, when the magnetic resistance of the iron coreis small, the impedance is generally determined only by the reactance.This value corresponds to the exciting impedance and is extremely large.When the low voltage switch 29 is closed to short the control winding37, a short-circuit current flows through the control winding 37,whereby the reactance component is erased and the impedance of thevariable reactor essentially consists only of the resistance component,the Value of the impedance being equal to the sum of the primaryresistance and the secondary resistance multiplied by the second powerof the turn ratio, and is so small as not to be greater than theone-tenth of the one in the case of the control winding 37 being open.

The chart of FIG. 5 shows how the impedance of the variable reactorvaries with the number of turns of the main winding, upon shorting oropening the control winding 37, the turn ratio of the variable reactoris 4. From this chart, it will be seen that the impedance varies largelyas the number of turns of the main winding increases. This is because,when the control winding is open, the reactance increases in proportionto the second power of the number of turns.

The chart of FIG. 6 shows how the impedance of the variable reactorvaries with the turn ratio (the number of turns of the main windingbeing constant). It will be understood from this chart that a greaterchange can be obtained when the turn ratio approaches 1. This is due tothe fact that the resistance component in the short-circuit conditiondecreases.

A practical example of the change in impedance of the variable reactoris gi-ven below: namely, when the number of turns of the main windingwas 3800 with a resistance value of 1116 ohms and the number of turns ofthe control winding was `600 with a resistance value of 47.07 ohms, theimpedance of the variable reactor was changed from 53,950 ohms when thecontrol winding was open, to 2960 ohms when the control winding wasshorted, the change ratio being about 18.

Since the high voltage relay is connected in series to the variablereactor whose impedance varies so sharply as described above, when theimpressed voltage is constant in FIG. 3, the voltage impressed on thehigh voltage relay and the variable reactor vary sharply upon opening orclosing the control winding. Namely, when the control winding is open,almost the entire voltage is borne by the Ivariable reactor but, whenthe control winding is shorted, some degree lof voltage is impressed onthe high voltage relay since the impedance of the variable reactordecreases. An example is shown in the table below.

From the above, it will be understood that a high voltage relay which isactuated by a voltage of the order of 50 v., will be able to close andopen the high voltage switch upon opening and shorting the controlwinding of the variable reactor.

The chart of FIG. 7 shows how the voltages impressed on the variablereactor and the high voltage relay vary with a power source voltage,upon opening or closing the switch connected to the control winding ofthe variable reactor.

In order to reduce the voltage to be impressed on the switch to a levelnot higher than 3() v. so as to eliminate the danger of electric shock,and to suppress the temperature rise of each component part under a lowlevel, it is necessary to properly select the shape and dimensions ofthe iron core, the number of turns and wire diameter of the main andcontrol winding ofthe variable reactor, and the number of turns and thewire diameter of the exciting winding of the high voltage relay. By sodoing, it is possible to obtain a vacuum cleaner with ease in whichremote control is possible even when used with a source voltage of 100v. to 2001 v. or higher.

As will be understood from the foregoing description, according to thepresent invention, the low voltage switch 29 and the circuit comprisingthe control winding of the variable reactorcan be completely separatedfrom the circuit comprising the main winding of said variable reactorelectrically. Therefore, insulation of the circuit comprising thecontrol winding or insulation of the leads 42 embedded in the flexiblehose, insulation of the connector 30 on the cleaner body side and theconnector 31 on the exible hose side and insulation of the low voltageswitch 29 can be obtained simply.

Even when the high voltage relay 38 is shorted with the main circuit 34of the electric blower 3 due to a faulty condition occurring in saidrelay, a high voltage will not be impressed on the circuit comprisingthe control winding of the variable reactor, i.e. the circuit composedof the connector 30 on the cleaner body side, the connector 31 on theilexible hose side, the leads 42 and the low voltage switch 29.Therefore, the operator will be able to operate the cleaner safely,without danger of being struck by electricity.

Further, the main winding 36 of the variable reactor 35 will not have ahigh voltage impressed directly thereon since said main winding 36 hasthe exciting winding 39 of the high voltage relay connected 4thereto inseries. This further enhances the safety of the vacuum cleaner. Stillfurther, the voltage impressed on the main winding of the variablereactor is reduced somewhat and accordingly the number of turns of themain winding 36 can be reduced. As a result, the entire variable reactorcan be reduced in size, necessitating only a small space to be providedin the cleaner body for installation.

Still further, since the exciting winding 39 of the high voltage relayis connected to the main winding 36 of the variable reactor in series,with a voltage always impressed thereon, the residual magnetismremaining in the magnetic circuit of the high voltage relay upon openingthe switch is erased by a slight current flowing therethrough andthereby erroneous operation of the high voltage relay can be eliminated.In addition, since the high voltage relay is not required to be operatedat a low voltage as is the case in a conventional remote controlcircuit, a wire with a small diameter can be used for the exciting coilof the relay. This is advantageous in reducing the cost and size of therelay.

We claim:

1. A vacuum cleaner comprising a high voltage motor, a va-riable reactorhaving a main circuit and a control circuit, a relay having a highvoltage switch for said motor and an exciting circuit to actuate saidhigh voltage switch connected to the main circuit of said variablereactor, and a low voltage switch provided on a diexible hose connectedto the cleaner body, said low voltage switch being electricallyconnected to the control circuit of said variable reactor, whereby, uponopening or closing of the low voltage switch, the high voltage switch inthe relay is opened or closed to rotate or stop the high voltage motor.

2. A vacuum cleaner comprising a high voltage motor, a variable reactorhaving a main circuit and a control circuit, a relay having a highvoltage switch to control said motor and an exciting circuit to actuatesaid high voltage switch, and a low voltage switch provided on a exiblehose connected to the cleaner body, said low voltage switch beingelectrically connected to the control circuit of said variable reactorto form a low voltage circuit, the exciting circuit of said relay beingelectrically connected to the main circuit of said variable reactor toform a high voltage circuit, and said low voltage circuit and said highvoltage circuit forming a remote control circuit.

3. A vacuum cleaner comprising a high voltage motor, a variable reactorhaving a low voltage control winding, a high voltage relay having anexciting winding connected to the main winding of said variablereactorto actuate a high voltage switch for said motor, and a manuallyoperative low voltage switch provided at the free end of a exible hoseconnected to the cleaner body, said low voltage control winding of saidvariable reactor being electrically connected to said low voltageswitch; and said high voltage motor, said high voltage switchelectrically connected to said high voltage motor in series, theexciting winding of said high voltage relay and the main winding of saidvariable reactor being impressed with a high voltage.

4. A vacuum cleaner comprising a high voltage motor, a variable reactorhaving a main winding and a control winding, a high voltage relay havinga high voltage switch to control said motor and an exciting winding toactuate said high voltage switch, and a low voltage switch provided on aflexible hose connected to the cleaner body, said low voltage switchbeing electrically connected to the control winding of said variablereactor and the exciting winding of said high voltage relay beingelectrically connected to the main winding of said variable reactor tohave a high voltage impressed thereon, whereby a current is kept flowingthrough said exciting winding even when the high voltage switch is openholding the motor inoperative.

References Cited' UNITED STATES PATENTS 2,958,894 11/1960 Carabet.

3,382,374 5/1968 Campbell 307--130 ROBERT W. MICHELL, Primary ExaminerU.S. Cl. X.R.

